The present invention relates to an improved formulation both for extinguishing fires and for decomposing (bioremediating) residual organic materials, including hydrocarbons, that were fueling the fire or that continue to create a hazard after the fire is extinguished. In particular, the present invention relates to an aqueous film forming foam (AFFF) fire-fighting formulation that also biodegrades in situ the residual hydrocarbons remaining at a fire site after the fire is extinguished, including biodegrading certain of the components of the fire-fighting formulation.
Without limiting the scope of the invention, its background is described in connection with uses of foaming concentrates for use as fire-fighting agents. Foaming concentrates for use as fire-fighting agents have been known and used since before 1940. Additional ingredients are added to such concentrates for a variety of reasons. For example, because such concentrates contain organic or proteinaceous foaming agent, microbicides (bactericides) are added to the concentrate to kill or prevent bacteria which would decay the foaming agent. Some typical foam fire-fighting formulations produce a foam that may persist for up to several days. Persistent foams have utility for such applications as temporary covers for landfills and waste piles, vapor barriers for spills of hazardous materials, and crop protection against frost. The presence of a bactericide in the foam to prevent the decomposition of the foam by bacteria promotes the persistence of the foam.
Examples of protein hydrolysates as a constituent of prior art foam formulations include U.S. Pat. No. 5,225,095 to DiMaio, and also U.S. Pat. No. 5,133,991 to Norman et al. Because these hydrolysates are excellent nutrient sources for microbiological life forms, a low-level toxicity microbicide or bactericide is usually recommended as an additive to preserve the concentrate. The fact that most foams are susceptible to microbial decomposition provides a basis for the conclusion that the art of fire-fighting foams teaches against the inclusion of microbial life forms in their formulations.
Organics decomposing microorganisms have been commercially available to clean oil spills from oil tankers and to assist in waste removal from grease interceptors in restaurants for some time now. Microbes specifically engineered for the decomposition of difficult organic compounds are well known and readily available.
Investigation of microbial degradation of oil dates back to at least 1942, when the American Petroleum Institute began to subsidize research in the field. Considerable basic knowledge about factors that affect natural biodegradation, the kinds of hydrocarbons capable of being degraded, and the species and distribution of the microorganisms involved in biodegradation had already been developed in the early 970s. For instance, the Office of Naval Research sponsored more than a dozen basic and applied research projects in the late 1960s and early 1970s on oil biodegradation to control marine oil spills. Since this time, a large number of refineries, tank farms, and transfer stations now employ in situ bioremediation to restore land contaminated by accidental spills of fuel oil or other hydrocarbons.
An important series of field tests of the use of fire-fighting foam to control organics and hydrocarbon fires were conducted in the aftermath of the Persian Gulf War. The oil field fires created an environment of urgency and necessity which focused creative minds on solving the problems at hand, and on concentrating on research and development to solve some of the problems anticipated to occur again in the future.
The difficulties encountered in incorporating microbe cultures in a fire-fighting foam solution which will extinguish organically fueled fires and begin the disposal of the residual hydrocarbon waste products were many. The first challenge was the selection of a hardy strain of organics-consuming (primarily hydrocarbon-consuming) microorganisms that can withstand the extremely severe environment associated with organically fueled fires in a proportion sufficient to adequately address the magnitude of the overall bioremediation challenge presented. A second challenge was determining the specific organism that digest or decompose a particular grease or oil and yet remain capable of being stabilized so that they have a satisfactory shelf life thereby being available when needed. A third challenge was the selection of a microbial strain that be stable in surfactant mixtures strong enough to extinguish the fire.
A need, therefore, exists for a bioremediating fire-fighting foam mixture and a method for the decomposition of organic materials which meets the challenges presented in order to reduce cleanup costs and increase the quality of the cleanup by providing an effective and environmentally safe means to do so.
The object of the present invention is to provide effective fire-fighting formulations that initiate bioremediation of the site of the fire. Generally, the invention is an aqueous formulation which includes preselected bioremediation agents in a fire-fighting foam-forming composition.
In one embodiment of the present invention, a composition for extinguishing fires and bioremediating a fire site is provided comprising a foam-forming surfactant component and a bioremedial component comprising one or more sporogenous nonpathogenic bacteria species. By foam-forming surfactant component is meant one or more surfactants including if desired mixtures of surfactants including anionic, cationic, non-ionic, and amphoteric surfactants. Certain of these surfactants may be fluorinated surfactants that provide a film-forming foam.
The bioremediation component comprises a biological agent having the characteristics: 1) the ability to at least partially degrade flammable organic materials; 2) the ability to remain viable in fire-fighting, foam-forming and the film-forming foam formulations; and 3) lack of pathogenicity in humans of normal vulnerability. Suitable microorganisms utilized in one embodiment of the present invention may include, for example, sporogenous bacteria embodying the desired characteristics. Certain commercially available sporogenous Bacillus strains, for example, include Bacillus formulated by Sybron Chemicals, Inc. Bacillus are a gram-positive bacterium which, under certain conditions, are spore-forming. Examples of Bacillus strains effective in the practice of the invention in connection with the consumption of volatile organic compounds include but are not limited to B. subtilis, B. licheniformis, B. polymyxa (now Paenibacillus polymyxa), B. amyloliquifaciens, B. pasteurii and B. laevolacticus. 
In addition, the selection among the above strains is advantageous because these species of Bacillus are not true pathogens as are the species B. anthracis and B. cereus. Reports of infections in man caused by Bacillus species other than B. anthracis and B. cereus are rare. According to a report by the Department of Biology of the Virginia Polytechnic Institute and State University, B. subtilis, B. licheniformis, and B. polymyxa as described by the manufacturer, Sybron, would not constitute a public health hazard unless the microorganisms were used in an area where individuals with an unusual vulnerability (such as with open wounds or immunodeficiency) would be exposed. Similarly, B. amyloliquifaciens, B. pasteurii and B. laevolacticus are considered not to constitute a public health hazard because they are not B. anthracis or B. cereus species.
Microorganisms (microbes) of the type used in the present invention are capable of assimilating and breaking down the non-soluble organic materials including hydrocarbons that compose grease and oil into relatively harmless substances of water-soluble products, carbon dioxide and a lesser quantity of fatty acids. The bacterial component may consist essentially of bacteria in aqueous solution or may include additional compounds such as surfactants, stabilizers, opacifiers, buffers, etc.
In one embodiment, the composition may include constituents designed to improve the film-forming characteristics of the foam. Surfactants comprising fluorinated surfactants are particularly advantageous because of their film-forming foam characteristics. The fluorinated, film-forming foam surfactant component may be a premixed solution comprising a number of constituents such as, for two examples not intended to be limiting as to the scope of the film-forming foam surfactant component, those represented by the surfactant formulations marketed under the trade names ZONYL FSA and LODYNE. In one embodiment, additional constituents designed to improve the integrity or homogeneity of the film-forming foam composition are added. Such additional constituents may include a solvent or water-based coupler such as for one example a glycol ether. A glycol ether found to be efficacious is diethylene glycol mono-butyl ether. Another additional constituent useful in certain formulations may be a polymer emulsifier or thickener, such as polysaccharide gum. One such polysaccharide gum found to be efficacious is a xanthan gum such as for example those marketed under the trade names KELZAN and XANVIS.
One particularly useful embodiment provides a composition comprising a fluorinated foam-forming surfactant component having a concentration of about 12-20% by volume in the composition, a concentration found to be efficacious is 15% LODYNE. This mixed in the inventive composition gives a total number of viable bacteria in the range of about 1xc3x97109 to about 5xc3x971011 per gallon in the final composition, a plurality species and quantity of such found to be efficacious is a mixture of B. subtilis, B. licheniformis, B. polymyxa (now Paenibacillus polymyxa), B. amyloliquifaciens, B. pasteurii and B. laevolacticus at a final concentration of about 6xc3x971010 viable bacteria per gallon of the final composition. This embodiment also includes a glycol ether at a of about 13-22% by volume in the composition, a glycol ether and concentration thereof found to be efficacious is 17% by volume diethylene glycol mono-butyl ether. This embodiment further includes a polysaccharide gum at a concentration of about 1-7% weight per volume in the composition, a xanthan gum such as that marketed under the trade name XANVIS at a concentration of 3.25 lbs/100 gallons of the final composition has been found to be efficacious.
Further provided is a method of simultaneously extinguishing a fire and bioremediating a site of the fire comprising the steps of applying to the fire a mixture comprising one or more foam-forming surfactants and a plurality of nonpathogenic sporogenous Bacillus species in sufficient quantity to seed the fire site after extinguishment of the fire and leaving at least a portion of the mixture at the fire site to effect bioremediation.
In an alternate embodiment, a foam-forming fire-fighting and bioremediating composition is provided comprising, in aqueous solution, a ALS foam-forming surfactant at a concentration of from about 30-40% by volume, a bioremediating bacterial component comprising from 10-25% per volume GC600L 6X, and a polysaccharide gum component comprising from 1-4% weight per volume of xanthan gum.
In alternate embodiments the invention may further provide inorganic nutrients in a concentration sufficiently small to avoid microbe activation in storage, stabilizers, emulsifiers, preservatives, or additional foaming agents, together with surfactants useful for extinguishing fires and bioremediating a fire site. Microorganisms in this mixture are stabilized until used and then activated when applied to waste organic compounds including hydrocarbons. The selection of specific activatable bioremediation agents, activatable microbes, microbe cultures, microorganisms, bacteria, spores, or sporogenous microbe strains could vary for additional efficacy, depending on the waste material to be remediated.
In broad practice, this invention comprises a bioremediating component in an aqueous solution and a fire-extinguishing component including a foaming agent. The organic materials that provide fuel for the fire also support the reproduction and growth of the microbe strains of the bioremediating component. They support the growth and reproduction of these strains when they are activated in the presence of such organic compounds and water. In one embodiment, the mixture contains from about 40% to about 50% by volume of water, from about 30% to about 40% by volume foaming agent and from about 16% to about 20% by volume of premixed microbe solution. One embodiment of this invention contains about 45% by volume of water, about 36.7% by volume foaming agent (e.g., ammonium lauryl sulfate), and about 18.3% by volume of the pre-mixed microbe solution. In some embodiments, the pre-mixed microbe solution itself contains surfactants to disperse and extinguish the fire and facilitate the decomposition of the volatile organic compounds by the microbe cultures. Stabilizers, preservatives, perfumes, and deodorants may optionally be included with the microorganism culture (microbes).
A preferred embodiment of the present invention is a formulation which will not only put out the fire, but reduce the hazard of re-ignition by forming a film and also will biodegrade the organic fuel that may have caused the fire through microbial decomposition of the most volatile organic wastes, particularly those of hydrocarbon fires. The end product of this decomposition is carbon dioxide, nonionic water soluble products, and new microbial biomass. It has been found through testing that the microbes of the bioremediating component of the present invention are effective in remediating many components of fluorinated surfactant formulations, such as found in Aqueous Film Forming Foam (AFFF) formulations.
The motivation for developing a formulation which included microbes for extinguishing fires was founded on an appreciation for the severe environmental impact the oil field fires and spills were having on the soil in Kuwait in the aftermath of the Persian Gulf War. A particularly hardy strain of bacteria that would be able to withstand the heat of a fire site immediately after extinction of a hydrocarbon fire was sought for the purpose of determining how soon after the conventional extinction of the flame a bioremediating solution could be applied and still survive in sufficient numbers to perform their function. Because of the time for emergency response where fire-fighting equipment is readily available is typically a short period, and because the procedure for testing the effectiveness of fire-fighting foams involves application after only thirty (30) seconds from ignition, the temperatures which microbes would be subjected to are quite lowxe2x80x94there was little or no concern that the microbe population would be severely curtailed when subjected to this relatively low level of heat. Later tests confirmed this beliefxe2x80x94when subjected to xe2x80x9c30 secondxe2x80x9d blaze tests, microbe survivability after extinction of the flames was as high as 66 percent. However, in Kuwait, where fires raged for several days before extinction, temperatures of the fire site immediately after the extinction of the flames were substantially higher, as high as 1800 degrees Fahrenheit in some instances. In addition, the ordinary ground temperatures in Kuwait average about 120 degrees Fahrenheit.
Recognizing the duty to help remediate the ecological catastrophe in progress in Kuwait, and the unique opportunity to conduct experiments in the severest of all earthly environments, trials using a spill-control formulation comparable to that of the present invention were commenced with rather surprising results. Not only did approximately thirty-three (33) percent of the microbes of the formulation survive the intense heat, but the formulation extinguished the fire within a period of time which indicated that the formulation might be effective as a fire-fighting agent, despite the fact that no foaming agents were present in the formulation at this time. Again, this was an unexpected resultxe2x80x94the goal of the application was merely to determine how soon the bioremediating agents could be applied to begin to decompose the organic compounds. Early analysis of the constituents of the formulation showed that the manufacturer of a proprietary constituent had permitted some residual alcohol to remain in the formulation. Alcohol of course is a combustible and its presence was not beneficial to the goal of extinguishing the flames. The alcohol was subsequently removed from the proprietary constituent with the result being improved fire-fighting characteristics of the formulation. It was also observed that the heat of the fire site shortly after the extinction of the blaze caused the sporogenous microbes to come out of spore and begin the work of decomposing the waste in a foreshortened period of time.
It should be emphasized that the microbes in the formulation do not help extinguish the firexe2x80x94water, such as for example, the water held on the top of the burning fuel by the foam-forming surfactant contained in the fire extinguishing component of the formulation actually extinguishes the flames and cools the surface of the organic waste (oil, the crude and the sludge) sufficiently to permit one-third of the bacteria applied to survive. Ordinary procedure in extinguishing fires is to overspray and to continue to apply the foam for at least one minute after the flames are extinguished. It is at this point that most of the surviving microbes are injected into the hazard. The surfactants in the formulation break down the volatiles, thereby preventing flashback or re-ignition. It does this in part by dispersing the volatile materials through the reduction of its surface tension and subsequent encapsulation of each dispersed droplet of the organic compounds by surfactant molecules. In addition, in the period of time beginning immediately upon application and extinction of the flames, it is the surfactant containing component and not microbial decomposition which prevents the flashback through a mechanism which breaks down the compounds, changing the molecular structure of some of the most volatile compounds such that the flash point is greatly reduced.
After extinguishment, the microbes of the present invention begin decomposition of the volatile hydrocarbon or organic compounds which cause the fire. After extinction of the flames, the presence of the surfactant continues to have a synergistic effect by aiding in the biodegradation process by cleaning away and dispersing the oil particles so that more surface area is exposed to organics-consuming microbes, thereby speeding the process of decomposition. The volatiles are then broken down even further through microbial decomposition such that they no longer constitute an immediate threat of re-ignition.
The use of the formulation of the present invention also reduces cost as it may no longer be necessary to mechanically remove contaminated soil after the fire is extinguishedxe2x80x94the formulation continues to remediate the products of the spill as long as the area is sufficiently moist, breaking the organic material down into carbon dioxide, water-soluble products and new biomass.
One aspect of this invention was the selection of bioremediation agents and, in particular, sporogenous microbe strains mentioned above which (1) are stable in a surfactant of sufficient strength to extinguish the flames and (2) able to survive the intense heat associated with such a fire site after extinction of the flames such that a significant population of the microbes are present and activated to begin the decomposition of the volatiles.
A goal of the present invention is to provide a combination of fire extinguishment and on-site bioremediation. Foam is desirable as an extinguishment medium to help get through the heat due to its insulating characteristics, thereby protecting the bacteria, and as a medium to transport the surfactant and the microbes to the source of the fire. The foam acts as an effective carrier for the water, microbes and possibly other surfactants and chemical antioxidant such that when it covers an area, the water is able to stay on the surface of the organic thereby extinguishing the flames. Surfactants contained therein are able to interact directly with the combusting surface of the organic compounds and may aid in extinguishment. Subsequent to the extinction of the flames, the activated microbes drop out of the foam and onto the volatiles immediately commencing the decomposition processxe2x80x94the microbes come out of spore and begin to attack the source of the fire, converting it into carbon dioxide, water-soluble products and microbial biomass.
Because of the beneficial effects of foam cited above, ammonium lauryl sulfate (ALS) may be added as a constituent to aid in the formation of foam. It should be understood that it will be readily apparent to those of ordinary skill in the art to use substitute foaming agents, in place of or in addition to ALS. However, ALS may be desirable for its effectiveness as well as its non-toxicity as is evident from its prevalent use in personal hygiene products such as shampoos. Environmental friendliness is also a consideration of the present inventionxe2x80x94with certain formulation embodiments of the present invention it has been determined that substantially all of the constituents will biodegrade in about thirty (30) days time, including surfactants and other constituents of foaming agents. However, it has been discovered that better protection against re-ignition or flash over is provided by a film-forming foam fluorinated surfactant and with the appropriate bioremediation agent, a composition AFFF can be made that is more environmentally friendly than ordinary, prior AFFF compositions.
An object of the present invention is a fire-fighting formulation having the capability to enhance the bioremediation of most components of a fluorinated surfactant either already present in the environment more advantageously or to bioremediate fluorinated surfactant contained in the present AFFF formulation itself when it is applied to a fire site. A fire site for present purposes is a location where there is increased risk of a fire or where a fire has occurred.